Abstract: An apparatus for successively positioning a series of radiographic film cassettes at a film-exposing station, comprising an endless chain, the links of which consisting of thin boxes hinged to one another and each adapted to receive a radiographic film cassette. The chain is trained on two rotatable drums of polygonal cross-section, the faces of which have a width equal to the length of a link. The distance between the drum axes is equal to the length of a link or to a multiple of said length. The pivotal axes are disposed parallel to a patient-examining plane and at a distance as small as possible from said plane without preventing rotation of the drums.